Technically speaking, the revenues and outlays of the Social Security trust funds and the Postal Service should not be included in any budget totals. However, one of the most cited budget numbers is the unified budget total, which includes the sum of on-budget and off-budget totals.

The Social Security trust funds currently have a multi-trillion dollar surplus. However, any excess money is automatically invested in US government debt, which is why there is always a fear of Social Security checks not being sent out whenever there is a budget crisis.